Polypropylene has been heretofore widely used as a thermoplastic molding material having high rigidity, heat resistance and transparency. However, the polypropylene is poor in flexibility and impact resistance, so that in order to improve these properties, a soft rubber component have generally been added to the polypropylene.
However, the addition of a soft rubber component to the polypropylene to obtain polypropylene compositions improved in the flexibility and impact resistance causes a problem that the heat resistance of the propylene is deteriorated. Such polypropylene compositions are also desired to be improved in low-temperature heat-sealing properties.
Accordingly, the advent of propylene compositions excellent in heat resistance and low-temperature heat-sealing properties as well as in flexibility and impact resistance has been desired.
Crystalline polypropylene films are widely employed particularly in the field of food packaging because of their excellent mechanical properties such as tensile strength, rigidity, surface hardness, impact resistance and cold temperature resistance, optical properties such as glossiness and transparency, and food hygienic properties such as nontoxicity and odorless properties. The crystalline polypropylene films shrink when heated to their heat-sealing temperature, and hence it is difficult to heat-seal the films having a single layer structure. Therefore, the crystalline polypropylene films are usually provided with a heat-sealing layer, which is generally formed from a polymer such as a low-density polyethylene or a propylene-ethylene random copolymer.
The polymer for forming the heat-sealing layer is required to have, for example, the following properties:
(1) The polymer can be heat-sealed at a temperature considerably lower than the substrate (crystalline polypropylene film); PA1 (2) The polymer is excellent in heat-sealing strength and has no change of the heat-sealing strength with time; PA1 (3) The polymer is excellent in bond strength to the substrate; PA1 (4) The polymer has transparency almost equal to or higher than that of the substrate; PA1 (5) The polymer can be stored without blocking; PA1 (6) The polymer does not adhere to bag making machines or fill-packaging machines; and PA1 (7) The polymer has high scratch resistance. PA1 (A) polypropylene in an amount of 5 to 95% by weight, and PA1 (B) a propylene-1-butene random copolymer in an amount of 95 to 5% by weight, based on the weight of the polypropylene and the propylene-1-butene random copolymer; PA1 said propylene-1-butene random copolymer (B) having the following properties: PA1 (5) the melting point Tm, as measured by a differential scanning calorimeter, is in the range of 60 to 140.degree. C., and the melting point Tm and the 1-butene constituent unit content M (% by mol) satisfy the following relation: EQU -2.6M+130.ltoreq.Tm.ltoreq.-2.3M+155; and PA1 (6) the crystallinity C, as measured by X-ray diffractometry, and the 1-butene constituent unit content M (% by mol) satisfy the following relation: EQU C.gtoreq.-1.5M+75. PA1 (a) a transition metal compound represented by the following formula (1): ##STR1## wherein M is a transition metal of Group IVa, Va or VIa of the periodic table, PA1 (b) (b-1) an organoaluminum oxy-compound, and/or (b-2) a compound capable of reacting with the transition metal compound (a) to form an ion pair; and, optionally, PA1 (c) an organoaluminum compound. PA1 (I) a crystalline polypropylene layer, and PA1 (II) a layer formed from the polypropylene composition of the present invention, which is laminated on at least one surface of the crystalline polypropylene layer (I). PA1 the polypropylene (A) in an amount of 5 to 50% by weight, and PA1 the propylene-1-butene random copolymer (B) in an amount of 95 to 50% by weight; or PA1 the polypropylene (A) in an amount of not less than 50% by weight and less than 90% by weight, and PA1 the propylene-1-butene random copolymer (B) in an amount of not less than 10% by weight and less than 50% by weight. PA1 (1) The propylene-1-butene random copolymer used in the invention is a random copolymer of propylene and 1-butene, and contains: PA1 constituent units from propylene in amounts of 50 to 95% by mol, preferably 60 to 93% by mol, more preferably 70 to 90% by mol, e.g. 70 to 87% by mol, and PA1 constituent units from 1-butene in amounts of 50 to 5% by mol, preferably 40 to 7% by mol, more preferably 30 to 10% by mol e.g. 30 to 13% by mol. PA1 (i) head-to-tail enchained propylene unit triad sequences and PA1 (ii) propylene unit-butene unit triad sequences consisting of propylene units of head-to-tail enchained propylene units and butene units and containing propylene units as the second units PA1 a first peak region (about 21.0 to 21.9 ppm), PA1 a second peak region (about 20.2 to 21.0 ppm), and PA1 a third peak region (about 19.5 to 20.2 ppm). PA1 (a) a transition metal compound described later; PA1 (b) (b-1) an organoaluminum oxy-compound, and/or PA1 and, optionally, PA1 (c) an organoaluminum compound. PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-ethylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-n-propylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-n-butylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-sec-butylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-t-butylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-n-pentylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-n-hexylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-cyclohexylindenyl)zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-methylcyclohexylindenyl)}zirconi um dichloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-phenylethylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-phenyldichloromethylindenyl)}zir conium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-chloromethylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-trimethylsilylenemethylindenyl)} zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-trimethylsiloxymethylindenyl)}zi rconium dichloride, PA1 rac-Diethylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium dichloride, PA1 rac-Di(i-propyl)silylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium dichloride, PA1 rac-Di(n-butyl)silylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium dichloride, PA1 rac-Di(cyclohexyl)silylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium dichloride, PA1 rac-Methylphenylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium dichloride, PA1 rac-Methylphenylsilylene-bis(1-(2,7-dimethyl-4-t-butylindenyl)}zirconium dichloride, PA1 rac-Diphenylsilylene-bis{1-(2,7-dimethyl-4-t-butylindenyl)}zirconium dichloride, PA1 rac-Diphenylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium dichloride, PA1 rac-Diphenylsilylene-bis{1-(2,7-dimethyl-4-ethylindenyl)}zirconium dichloride, PA1 rac-Di(p-tolyl)silylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium dichloride, PA1 rac-Di(p-chlorophenyl)silylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirco nium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-i-propyl-7-ethylindenyl)zirconium dibromide, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium dimethyl, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium methylchloride, PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium-bis(t rifluoromethanesulfonato), PA1 rac-Dimethylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium-bis(p -phenylsulfinato), and PA1 rac-Dimethylsilylene-bis{1-(2-phenyl-4-i-propyl-7-methylindenyl)}zirconium dichloride. PA1 rac-Dimethylsilylene-bis{1-(4-phenylindenyl) }zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(.alpha.-naphthyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(.beta.-naphthyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(1-anthracenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(2-anthracenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(9-anthracenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(9-phenanthryl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(p-fluorophenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(pentafluorophenyl)indenyl)}zirconiu m dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(p-chlorophenyl)-1-indenyl)}zirconiu m dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(m-chlorophenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(o-chlorophenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(o,p-dichlorophenyl)indenyl)}zirconi um dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(p-bromophenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(p-tolyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(m-tolyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(o-tolyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(o, o'-dimethylphenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(p-ethylphenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(p-i-propylphenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(p-benzylphenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(p-biphenylyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(m-biphenylyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(p-trimethylsilylenephenyl) indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-(m-trimethylsilylenephenyl)indenyl)} zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-phenyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Diethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Di(i-propyl)silylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Di(n-butyl)silylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dicyclohexylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Methylphenylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Diphenylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Di(p-tolyl)silylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Di(p-chlorophenyl)silylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Methylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Ethylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylgermylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylstannylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dibromide, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dimethyl, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium methylchloride, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium chloride SO.sub.2 Me, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium chloride OSO.sub.2 Me, PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium mono(trifluoromethanesulfonate), PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium di(trifluoromethanesulfonate), PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium di(p-toluenesulfonate), PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium di(methylsulfonate), PA1 rac-Dimethylesilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium di(trifluoroacetate), PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium monochloride mono(n-butoxyde), PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium di(n-butoxyde), PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium monochloride mono(phenoxyde), PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}titanium dichloride, and PA1 rac-Dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}hafnium dichloride. PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(.alpha.-naphthyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(.beta.-naphthyl)indenyl}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(2-methyl-1-naphthyl)indenyl}zirconiu m dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(5-acenaphthyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(9-anthracenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(9-phenanthryl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(o-methylphenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(m-methylphenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(p-methylphenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(2,3-dimethylphenyl)indenyl)}zirconiu m dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(2,4-dimethylphenyl)indenyl)}zirconiu m dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(2,5-dimethylphenyl)indenyl)}zirconiu m dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(2,4,6-trimethylphenyl)indenyl)}zirco nium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(o-chlorophenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(m-chlorophenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(p-chlorophenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(2,3-dichlorophenyl)indenyl)}zirconiu m dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(2,6-dichlorophenyl)indenyl)}zirconiu m dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(3,5-dichlorophenyl)indenyl)}zirconiu m dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(2-bromophenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(3-bromophenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(4-bromophenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(4-biphenylyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-ethyl-4-(4-trimethylsilylphenyl)indenyl)}zirc onium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-propyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-propyl-4-(.alpha.-naphthyl)indenyl)}zirconi um dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-propyl-4-(.beta.-naphthyl)indenyl)}zirconiu m dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-propyl-4-(2-methyl-1-naphthyl)indenyl)}zirc onium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-propyl-4-(5-acenaphthyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-propyl-4-(9-anthracenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-propyl-4-(9-phenanthryl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-i-propyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-i-propyl-4-(.alpha.-naphthyl)indenyl)}zirconi um dichloride, PA1 rac-Dimelhylsilylene-bis{1-(2-i-propyl-4-(.beta.-naphthyl)indenyl)}zirconiu m dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-i-propyl-4-(2-methyl-1-naphthyl)indenyl)}zirc onium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-i-propyl-4-(5-acenaphthyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-i-propyl-4-(9-anthracenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-i-propyl-4-(9-phenanthryl)iridenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis1-(2-s-butyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-s-butyl-4-(.alpha.-naphthyl)indenyl)}zirconiu m dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-s-butyl-4-(.beta.-naphthyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-s-butyl-4-(8-methyl-9-naphthyl)indenyl)}zirco nium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-s-butyl-4-(5-acenaphthyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-s-butyl-4-(9-anthracenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-s-butyl-4-(9-phenanthryl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-pentyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-pentyl-4-(.alpha.-naphthyl)indenyl)}zirconi um dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-butyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-butyl-4-(.alpha.-naphthyl)indenyl)}zirconiu m dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-butyl-4-(.beta.-naphthyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-butyl-4-(2-methyl-1-naphthyl)indenyl)}zirco nium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-butyl-4-(5-acenaphthyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-butyl-4-(9-anthracenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-butyl-4-(9-phenanthryl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-i-butyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-i-butyl-4-(.alpha.-naphthyl)indenyl)}zirconiu m dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-i-butyl-4-(.beta.-naphthyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-i-butyl-4-(2-methyl-1-naphthyl)indenyl)}zirco nium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-i-butyl-4-(5-acenaphthyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-i-butyl-4-(9-anthracenyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-i-butyl-4-(9-phenanthryl)indenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-neopentyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-neopentyl-4-(.alpha.-naphthyl)indenyl)}zircon ium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-hexyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylsilylene-bis{1-(2-n-hexyl-4-(.alpha.-naphthyl)indenyl)}zirconiu m dichloride, PA1 rac-Methylphenylsilylene-bis{1-(2-ethyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Methylphenylsilylene-bis{1-(2-ethyl-4-(.alpha.-naphthyl)indenyl)}zircon ium dichloride, PA1 rac-Methylphenylsilylene-bis{1-(2-ethyl-4-(9-anthracenyl)indenyl)}zirconium dichloride, PA1 rac-Methylphenylsilylene-bis{1-(2-ethyl-4-(9-phenanthryl)indenyl)}zirconium dichloride, PA1 rac-Diphenylsilylene-bis{1-(2-ethyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Diphenylsilylene-bis{1-(2-ethyl-4-(.alpha.-naphthyl)indenyl)}zirconium dichloride, PA1 rac-Diphenylsilylene-bis{1-(2-ethyl-4-(9-anthracenyl)indenyl)}zirconium dichloride, PA1 rac-Diphenylsilylene-bis{1-(2-ethyl-4-(9-phenanthryl)indenyl)}zirconium dichloride, PA1 rac-Diphenylsilylene-bis{1-(2-ethyl-4-(4-biphenylyl)indenyl)}zirconium dichloride, PA1 rac-Methylene-bis{1-(2-ethyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Methylene-bis{1-(2-ethyl-4-(.alpha.-naphthyl)indenyl)}zirconium dichloride, PA1 rac-Ethylene-bis{1-(2-ethyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Ethylene-bis{1-(2-ethyl-4-(.alpha.-naphthyl)indenyl)}zirconium dichloride, PA1 rac-Ethylene-bis{1-(2-n-propyl-4-(.alpha.-naphthyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylgermylene-bis{1-(2-ethyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylgermylene-bis{1-(2-ethyl-4-(.alpha.-naphthyl)indenyl)}zirconium dichloride, PA1 rac-Dimethylgermylene-bis{1-(2-n-propyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylstannylene-bis{1-(2-ethyl-4-phenylindenyl)}zirconium dichloride, PA1 rac-Dimethylstannylene-bis{1-(2-ethyl-4-(.alpha.-naphthyl)indenyl)}zirconiu m dichloride, PA1 rac-Dimethylstannylene-bis{1-(2-n-ethyl-4-(9-phenanthryl)indenyl)}zirconium dichloride, and PA1 rac-Dimethylstannylene-bis{1-(2-n-propyl-4-phenylindenyl)}zirconium dichloride. PA1 trialkylaluminums, such as trimethylaluminum, triethylaluminum, tripropylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-sec-butylaluminum, tri-tert-butylaluminum, tripentylaluminum, trihexylaluminum, trioctylaluminum and tridecylaluminum; PA1 tricycloalkylaluminums, such as tricyclohexylaluminum and tricyclooctylaluminum; PA1 dialkylaluminum halides, such as dimethylaluminum chloride, diethylaluminum chloride, diethylaluminum bromide and diisobutylaluminum chloride; PA1 dialkylaluminum hydrides, such as diethylaluminum hydride and diisobutylaluminum hydride; PA1 dialkylaluminum alkoxides, such as dimethylaluminum methoxide and diethylaluminum ethoxide; and PA1 dialkylaluminum aryloxides, such as diethylaluminum phenoxide. PA1 trialkylaluminums, such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trioctylaluminum, tri(2-ethylhexyl)aluminum and tridecylaluminum; PA1 alkenylaluminums, such as isoprenylaluminum; PA1 dialkylaluminum halides, such as dimethylaluminum chloride, diethylaluminum chloride, diisopropylaluminum chloride, diisobutylaluminum chloride and dimethylaluminum bromide; PA1 alkylaluminum sesquihalides, such as methylaluminum sesquichoride, ethylaluminum sesquichloride, isopropylaluminum sesquichloride, butylaluminum sesquichloride and ethylaluminum sesquibromide; PA1 alkylaluminum dihalides, such as methylaluminum dichloride, ethylaluminum dichloride, isopropylaluminum dichloride and ethylaluminum dibromide; and PA1 alkylaluminum hydrides, such as diethylaluminum hydride and diisobutylaluminum hydride. PA1 the component (b-1) (or the component (b-2)) is mixed with the component (a); PA1 the compcnent (b-1) is first mixed with the component (c) and then with the component (a); PA1 the component (a) is first mixed with the component (b-1) (or the component (b-2)) and then with the component (c); or PA1 the component (a) is first mixed with the component (c) and then with the component (b-1) (or the component (b-2)). PA1 the polypropylene (A) in an amount of 5 to 95% by weight, preferably 20 to 90% by weight, more preferably 40 to 85% by weight, and PA1 the propylene-1-butene random copolymer (B) in an amount of 95 to 5% by weight, preferably 80 to 10% by weight and 60 to 15% by weight. PA1 MgAl.sub.2 (OH).sub.20 CO.sub.3.5H.sub.2 O, PA1 Mg.sub.5 Al.sub.2 (OH).sub.14 CO.sub.3.4H.sub.2 O, PA1 Mg.sub.10 Al.sub.2 (OH).sub.22 (CO.sub.3).sub.2.4H.sub.2 O, PA1 Mg.sub.6 Al.sub.2 (OH).sub.16 HPO.sub.4.4H.sub.2 O, PA1 Ca6Al.sub.2 (O).sub.16 CO.sub.3.4H.sub.2 O, PA1 Zn.sub.6 Al.sub.2 (OH).sub.16 CO.sub.3.4H.sub.2 O, PA1 Zn.sub.6 Al.sub.2 (OH).sub.16 SO.sub.4.4H.sub.2 O, PA1 Mg.sub.6 Al.sub.2 (OH).sub.16 SO.sub.3.4H.sub.2 O and PA1 Mg.sub.6 Al.sub.2 (OH).sub.12 CO.sub.3.3H.sub.2 O. PA1 powdery fillers, for example, natural silicic acids or silicates such as fine-powdery talc, kaolinite, calcined clay, pyrophyllite, sericite and wollastonite, carbonates such as precipitated calcium carbonate, ground limestone and magnesium carbonate, hydroxides such as aluminum hydroxide and magnesium hydroxide, oxides such as zinc oxide, zinc white and magnesium oxide, and synthetic silicic acids or silicates such as hydrated calcium silicate, hydrated aluminum silicate, hydrated silicic acid and silicic anhydride; PA1 flaky fillers, such as mica; PA1 fibrous fillers, such as basic magnesium sulfate whisker, calcium titanate whisker, aluminum borate whisker, sepiolite, PMF (Processed Mineral Fiber), xonotolite, potassium titanate and ellestadite; and PA1 balloon fillers, such as glass balloon and fly ash balloon. PA1 (I) a crystalline polypropylene layer, and PA1 (II) a layer formed from the polypropylene composition of the present invention, which is laminated on at least one surface of the crystalline polypropylene layer (I). PA1 (1) The copolymer contains units from propylene in an amount of 50 to 95% by mol, preferably 55 to 93% by mol, more preferably 60 to 90% by mol, and contains units from 1-butene in an amount of 5 to 50% by mol, preferably 7 to 45% by mol, more preferably 10 to 40% by mol.
However, the conventional heat-sealing materials do not always satisfy all of these properties. For example, though the low-density polyethylene can be heat-sealed at a low temperature, it is poor in the heat-sealing strength and bond property to the substrate and easily adheres to the packaging machines or the like.
The propylene-ethylene random copolymer satisfies the above properties (2) to (7), but does not satisfy the property (1). For example, a polypropylene composite film having a heat-sealing layer of the propylene-ethylene random copolymer has a harrow heat-sealing temperature range. Therefore, when the composite film is heat-sealed by means of an automatic packaging machine or an automatic bag making machine, the heat-sealing temperature must be strictly controlled. It has been proposed to use a blend of the propylene-ethylene random copolymer and an ethylene-.alpha.-olefin copolymer as a heat-sealing material. However, this blend is poor in the transparency, though it is more improved in the low-temperature heat-sealing properties as compared with the propylene-ethylene random copolymer.
The present inventors have found that a propylene-1-butene random copolymer having a propylene content of 55 to 85% by weight and a heat quantity of crystal fusion (measured by a differential scanning calorimeter) of 20 to 80 J/g has high transparency and good low-temperature heat-sealing properties and thus is useful as a heat-sealing material. Based on these findings, the present inventors have proposed to use, as a heat-sealing layer for a polypropylene film, a composition which comprises the propylene-1-butene random copolymer and an isotactic polypropylene (Japanese Patent Laid-Open Publication No. 114887/1979). The heat-sealing layer formed from this composition is excellent in the low-temperature heat-sealing properties and blocking resistance, but it is a little inferior in the blocking resistance and scratch resistance to the heat-sealing layer formed from the propylene-ethylene random copolymer.
The present inventors have also proposed, as a composite film of high heat-sealing properties, a composite film consisting of an isotactic polypropylene film and a heat-sealing layer formed from a composition which comprises 10 to 40% by weight of a propylene-1-butene copolymer and a crystalline propylene-.alpha.-olefin random copolymer (Japanese Patent Publication No. 42626/1986).
The polypropylene films described above are desired to have further properties such that the films are applicable to high-speed packaging. Thus, the films are desired to have, for example, not only improved low-temperature heat-sealing properties and hot tack properties but also improved slip properties and blocking resistance.
Under such circumstances as mentioned above, the present inventors have studied polypropylene compositions comprising polypropylene and a rubber component, and have found that use of polypropylene and a specific propylene-1-butene random copolymer makes it possible to prepare a polypropylene composition excellent in heat resistance and low-temperature heat-sealing properties as well as in flexibility and impact resistance. The present inventors have also found that a polypropylene film having a heat-sealing layer made of the above-mentioned polypropylene composition has desired properties for applying to the high-speed packaging, such as not only excellent low-temperature heat-sealing properties and hot tack properties but also excellent slip properties and blocking resistance. Moreover, the present inventors have found that the specific propylene-1-butene random copolymer can be prepared using a specific metallocene compound catalyst component. Based on these findings, the present invention has been accomplished.